Printing plates and methods and apparatus for forming them



Feb. 27, 1962 F. HELLER 3,0

PRINTING PLATES AND METHODS AND APPARATUS FOR FORMING THEM Filed Nov.12, 1959 4 SheetsSheet 1 20 PRIOR ART E PRIOR ART ATTORNEYS Feb. 27,1962 F. HELLER 3,022,728

PRINTING PLATES AND METHODS AND APPARATUS FOR FORMING THEM Filed Nov.12, 1959 4 Sheets-Sheet 2 ATTORNEYS Feb. 27, 1962 F. HELLER 7 3,022,728

PRINTING PLATES AND METHODS AND APPARATUS FOR FORMING THEM Filed Nov.12, 1959 4 Sheets-Sheet 5 ATTORNEYS INV EN TOR Feb. 27, 1962 F. HELLER3,022,728

PRINTING PLATES AND METHODS AND APPARATUS FOR FORMING THEM Filed Nov.12, 1959 4 Sheets-Sheet 4 ATTORNEY5 ilnited rates Rateat 3,022,728PRIN'IWG PLATEE AND METHGDS AND APPARA'IUE FUR FQRMING THEM FranzHeller, Mount Vernon, N.Y., assignor to American Type Founders Ce. Inc,Elizabeth, N..I., a corporation of Delaware Filed Nov. 12, 1959, er. No.852,260 3 Claims. (Cl. Mil-415.1)

This invention relates to certain preparatory steps concerned with themake-ready of a lithographic printing press, for example one of the Webfed offset type, and has as its principal object the provision of anovel plate construction and of novel and improved methods and apparatusfor properly forming and applying the printing plates to the platecylinders of the press.

Workers in the printing industry are aware that the metal printingplates used in high-speed web offset presses must be very accuratelyapplied to the cylinders for quality production, the height orprojection of the surface of the plates above the cylinder bearers beingmeasured in thousandths of an inch. To this necessity of accuratepacking and securing of the plates must be added the care in insuringthat the plates are formed in the bending jig to the exact lengthappropriate to the circumference of the cylinders. Otherwise the plateis not securely held and continual flexing of the plate during operationof the press will cause the plate to crack, especially during long runs.This is particularly true in the case of aluminum plates.

Research by the applicant has also revealed another contributing factorin this proneness of the plate to crack. This further source ofdifficulty arises especially where a single reel-rod is employed in thecylinder gap such a reel-rod functioning not only to pull the tail edgeof the plate taut but to clamp or wedge the bent portion of the leadingedge against an inwardly angled wall of the cylinder gap.

Now the conventional bending of the leading edge of the plate to anacute angled configuration prepares it to fit over the similarly angledportion of the cylinder ad jacent the gap, but no such strong pull iseffected at the leading edge as is applied to the tail edge of the plateby the rotation of the reel-rod. As a consequence, it is difficult toinsure that the curvature of the plate near its bent or hooked leadingedge will conform to the exact radius of the cylinder. Thus there occursa slight hump in the plate at this point with a minute air space formedbetween the humped portion of the plate and the cylinder body.Furthermore, the material of which the plate is made is under somestress adjacent the hump or bend, the outer surface of the plateprobably being under tension and the inner surface under compressionstresses of varying degrees. During the printing operation, as the formrollers and the blanket cylinder pass over this bump, the plate will bealternately depressed and released, and this repeated flexing of theplate will add further stress to the already stressed plate and cause itto crack, with the resulting added costs and inconvenience.

It has been suggested that this difliculty might be overcome byproviding reel-rods for both ends of the plate in order to draw theplate more snugly against the cylinder at the forward end in the samemanner that the reel rod accomplishes this purpose at the tail end, butthese accessories occupy considerable space and increase printing costs,and would necessitate a much wider and uneconomical non-printingcylinder gap.

It is therefore an object of the present invention to provide novelmethods and means for eliminating the formation of such a stressed humpin the plate near its leading edge, while at the same time preservingthe accuracy of gauging the length of the plate in accordance aaza'zztPatented Feb. 27, 1952 with the circumference of the curved portion ofthe plate cylinder.

The invention contemplates the provision of a deliberately pre-formedbend or curvature just inwardly of the bent or hooked leading edge ofthe plate, this curva plate bending jig by means of which thispre-forming adjacent the leading edge may be accomplished.

Other objects and features of novelty will be apparent from thefollowing specification in which one embodiment of the invention isillustrated by way of example.

In the drawings:

FIGURE 1 is a somewhat diagrammatic View in side elevation of a printingplate in fiat form after it has come out of a bending jig ofconventional construction;

FIGURE 1A is a fragmentary diagrammatic view in end elevation of a platecylinder showing. in somewhat exaggerated style the initial applicationof the forward acutely bent portion of the plate as it is applied to thecylinder gap;

FIGURE 2 is a similiar view in somewhat exaggerated style thedestructive hump formed in the plate bent in the usual way adjacent thecylinder gap;

FIGURE 3 is a view similar to FIGURE 1 showing the pre-formed bend orcurvature provided in the plate adjacent its leading edge according tothe provisions of the present invention;

FIGURE 4 is a view similar to FIGURE 2 showing the snug application ofthe plate of such novel configuration to the plate cylinder;

FIGURE 5 is a somewhat diagrammatic view in side elevation of a jigembodying the principles of the invention;

FIGURE 6 is a view in end elevation of the jig as viewed from the leftin FIGURE 5;

FIGURE 7 is a fragmentary enlarged view in side elevation of theleft-hand end of the jig with certain parts shown in section, as alongline 7-7 of FIGURE 6;

FIGURE 8 is a further sectionalized view of the same portion of the jig,for example, as taken on line 88 of FIGURE 6;

FIGURE 9 is a fragmentary sectional view taken on line 9-9 of FIGURE 6;

FIGURE 10 is a detail sectional view taken on line 1ll-l0 of FIGURE 6;

FIGURE 11 is a fragmentary View in side elevation of the right-hand endof the jig as viewed in FIGURE 5;

FIGURE 12 is a plan view of the jig showing certain gauging means forinsuring the proper positioning of a plate for bending; said means forthe most part having been omitted from the precedin figures for the sakeof simplicity and clearness of illustration;

FIGURE 13 is a fragmentary plan view of a portion of the jig includingcertain optical gauging means;

FIGURE 13A is a fragmentary plan view in perspective of a portion of theupper surface of a plate showing the gauge marks used in positioning'it;and

FIGURE 14 is a fragmentary view in vertical section taken on line 14-14of FIGURE 12.

In the views illustrative of the prior art set forth in FIGURES 1, 1A,and 2 of the drawings, the conventional printing plate which may be ofzinc, copper, aluminum, or other substances familiar in the art, isdesignated generally by the reference numeral 10 and comprises a flatarea 11 constituting the major portion of the plate and carrying theprinting areas thereof. At the left-hand end of the plate the leadingedge is folded downwardly s eaves In FIGURES 1A and 2 the plate cylinderis given the general designation 2t? and is provided with a gap 21having a narrowed portion 22 between projecting noselike edges of thebody of the cylinder indicated at 23 and,

24. Within the wider inward portion 25 of the gap a reel-rod 26' (FIGURE2) is positioned for manual adjustment. The conventional plate It) isapplied to the periphery of the plate cylinder 26 with the bent'portion12 of the leading edge hooked around the nose 23 of the cylinder body(see FEGURE 1A), as well as the acute angling of this portion of theplate permits. The extreme bent section 14 of the tail edge is grippedwithin the cleft 28 of the reel-rod and the circumference of thereel-rod 26 exerts a pull on the tail of' the plate It which due to theobtuse angular disposition of the tail flange 13 not only exerts thetension on the plate in a generally lengthwise direction but also drawsit inwardly and quite snugly against the adjacent nose portion 24 f thegap 21.

Now in the case of the prior art plate illustrated diagrammatically inFIGURE I, the head end portion of thev plate adjacent the frontor headflangev 12 tends to retain its acute angularity and the exposed portionof the plate to remain in a somewhat straight line, suggested at a,tangent to the circumference of, the cylinder. This results from thelack of' a direct inward pull as applied to the tail flange by a reelrod. Then when the leading flange 12 is wedged against the inner wallsurface 29 of the cylinder gap, along with the tail flange 13, thewedging and frictional efifect applied by the reel rod exerts a pullalong this wall 29, and not by way of the obtuse angle by which the tailflanges are drawn by the reel rod. This results in the formation of acurved or humped portion in the plate adjacent the apex of the bend ofthe flange 12 as shown in FIGURE 2 of the drawings in somewhatexaggerated form, an air space 31 being left beneath this portion of theplate. Also, the plate adjacent this raised, humped, or curved area isunder stress, and it is understandable that the humped area will haveadditional stresses applied to it in rapid alternation during thecontinual high speed rotation of the plate cylinder in contact with theblanket cylinder and the associated inking system, and this, especiallyin-long runs, will cause the plate to crack adjacent the hump and theleading flange- The application of a plate such as indicated at 10 andformed in a conventional jig in accordance with present practicesinvariably results in the formation of a hump portion indicated at 30 inFIGURE 2 of the drawings, an air space 31 being left beneath thisportion of the plate as shown. It will be very obvious that thecontinual high speed rotation of the plate cylinder in contact with theblanket cylinder and the inking system will result in such a flexingwhich, especially in long runs, will cause the plate to crack adjacentthe hump portion.

So much for the existing situation with respect to conventional devicesof this nature. Now, referring particu larly to FEGURES 3 and 4 of thedrawings,- it will be seen that the novel plate conformation provided'bythe present invention and indicated generally by the reference numeralt? comprises a similar level portion 51 before it is applied to thecylinder, but toward the leading edge of the plate this major portion ofthe plate is given a definite downward curvature as shown at 55 Thedownwardly curved portion 55 terminates in the usual hook portion 52 atthe leading edge of the plate. The plate at its tail end terminates inthe double bend 53 and 54 as in the earlier described structure FIGURE 4merely shows the novel plate structnre 50 applied to the plate cylinder20 the major intelligence bearing portion 51 being wrapped around thecylinder in the usual way with the leading edge flange. or hook pot.-

tion 52 clamped in the gap 21 by means of the reel-rod 26 which gripsthe tail' areas 53 and 5d and holds both ends of the plate firmlygripped within the gap. It will be noted that at the additional inwardlybent area 55 the plate hugs the cylinder surface snugly and the humpsuch as shown atBtl in FIGURE 2 is completely eliminated.

Bearing in mind that the aim of the provision of the curvature or bend55is to cause the plate at this point to hug the underlying surface ofthe cylinder more closely in spite of the sharpness of the angularity ofthe flange 52, it will be readily understood that the degree ofprebending at 55 will vary somewhat depending upon the size of thecylinder, the thickness of the plate, and the material of which it isformed, as Well as the temper or hardness of the plate material.Furthermore, the curvature of the bend, that is the radius indicated airin FIG- URE 3, is not critical and becomes even less so as the diametersof the cylinders increase. However, it might be mentioned that theradius r will in most cases beless than the radius of the cylinderitself since in the case of a plate of more than usual resilience, aslight overbending may be necessary to compensate for any sprin backwhich might occur. Thus, it may be stated broadly. that the radius rmaybe anywhere from that of the cylinder down to a value considerablyless than the radius Of the, cylinder.

Theprocess thus, described may be carriedout by. means of the novelplate bending jig which is given the general designation 64 asilustrated in the remaining fig ures of drawing. In the somewhatdiagrammatic view comprising FIGURE 5, it will be seen that the body ofthe jig 66 comprises two base blocks 61 and 62, these plate to conformto the circumference of the particular plate cyiinder, a space 64 beingleft between the blocks 61 and 62 for this purpose.

The left-hand base block 61 is formed at its extremity with a projectingledge or nose portion 65 which is most clearlyshown in FIGURES 7 and 8of the drawings. The angularity of this projecting ledge may of coursevary somewhat and a suggested angle useful for most purposes isapproximately 35. The extreme apex or point 66 of the ledge 65 isslightly rounded, preferably on a radius of approximately 0.05 of aninch, taken on the center of the pintle 76.

However, the most radical feature of the bending ledge 65 is theprovision of the curvature near the extreme edge thereof in the areadesignated 79. This curvature is provided in order to form thepreliminary bend 55 in the plate 59 adjacent the leading edge.

Extending from each side of the left-hand edge of the base block 61 area pair of brackets 72, theserather fiat brackets being secured to therespective sides of the base 60 as by means of the screws 73. Thesebrackets 72 have projecting ears provided with registered threadedopenings 75. Pintles 76 are threaded into the openings 75, each of thesepintles having an inwardly projecting attenuated unthreaded portion 77terminating in a rounded tip 78. Fixed to the outer ends of the spindles76 are the hand wheels or knobs 79.

A bending bar 80 extends transversely across the jig just off of thenose or ledge portion 65 and is provided at each of its ends with ahinge bracket plate 81, these plates being provided with openings 82 toreceive the cylindrical portion 77 of the pintle or spindle members 76.Thus, the bending bar 80 is mounted with one of the lower cornersthereof substantially coinciding with the apex or ultimate edge 66 ofthe bending ledge 65. Extending outwardly from the bar'80 is the bracingand supporting fr mework 85 surmounted by the handle por- Each of thebrackets 72 tending vertically downwardly therethrough and adapted tofixedly secure the lower ends of the pins or posts indicated at 88.These openings occur just beneath the curved portion 70 of the bendingledge 65, and immediately above this curved portion is positioned thepreliminary bending and clamping bar 90 which has a bottom surface 91conforming to the curvature of the portion 70 of the block 61 and of thedesired preliminary bend to be impressed upon the plate 50 adjacent itsleading edge. The clamp bar 90 is provided at its left-hand end asviewed in FIGURE 6 with a notch or kerf 92 extending in the longitudinaldirection, and at its righthand end with a transversely extending notchor kerf 94. The end notch 92 virtually comprises a fork which is made tostraddle the intermediate portion of the threaded post 88 at that end ofthe device, the lower end of the cylindrical wheeled head 95 threadedupon the spindle bearing downwardly upon the upper surface of that endof the clamping bar 90 adjacent the kerf 92. The right-hand end of theclamp bar 90 may be swung into position beneath the wheeled head 96applied to the post 88 at that end of the clamp bar so that the notch orkerf 94 embraces the stem of the spindle as most clearly shown in FIGURE9 of the drawings. The head 96 threaded onto the post 88 at this end ofthe device bears downwardly upon the upper surface of the clamp ing bar90 as in the case of the left-hand end.

The clamping bar 90 is provided with a bowed truss element 98 to insureits rigidity.

In order to facilitate the installation of the bending bar 80 upon thespindles 76, a pair of rests or supporting brackets 100 are secured tothe bending bar 80 and have portions 101 which overlie the clamp bar' 90and are allowed to rest upon the clamp bar in order to support theweight of the bending bar during the time that the spindles 76 arethreaded through the openings 75 in the hanger brackets 72.

At the tail end of the jig, as indicated in FIGURES 5 and 11, there isprovided a clamp bar 110 which in most respects is the counterpart ofthe clamp bar 90 at the leading end, except that the bottom surface 111is perfectly flat and not provided with a curve such as characterizesthe leading edge of the arrangement. Stiffening and bracingsuperstructure 112 is provided for the clamping bar and the bar 110 isbrought to bear downwardly upon the plate as by means of the hand wheelsor knobs 95' and 96.

In order to throw the double bend into the tail end of the plate asrepresented by the parts 53 and 54 a bending bar 125 is provided, thisbending bar being provided at each end with the hinge plate 126 which isadapted to be connected by a pintle 127 with the corresponding hingeplate 128 secured to the tail end of the base block 62 of the jig.Obviously, the pintle 127 is centered upon the edge or corner 129 of theblock 62. The end of the block 62 is provided with a sloping surface 130which merges at 131 with the downwardly and inwardly inclined surface132. The bending bar 125 has a fiat lower surface 136 and a supplementalbar 140 is secured to the side of the bending bar 125, this supplementalbar being provided with an inclined surface 142.

The bending bar 125 is provided with a stiffening superstructure 145surmounted by an operating handle 146 as in the case of the bending bar80 at the other end of the ig.

Referring now more particularly to FIGURES 12 to 14 of the drawings,certain gauge devices for properly positioning the plate on the jig willbe described. Midway along each side of the body of the jig 60, bridgingthe gap 64 between the blocks 61 and 62, are the fixed plates or inserts150. These small plates have inscribed thereon, with a great degree ofaccuracy, the rectilinear gauge markings 151. These gauge marks projectslightly beyond the end margins of the printing plate P indicated isprovided with openings exby the lines 152. Similar register marks 151'are inscribed on the printing plate and these are brought into exactalignment with the gauge marks 151 on the insert Other and somewhat moreaccurate gauging and aligning means are provided by the optical devicescommonly called scopes and indicated at 155, 156, 157 and 158 in FIGURE12 of the drawings. Two of these scopes, dessignated 155 and 156, arecarried by brackets 160 and 161, which are disposed at an angle withrespect to the margin of the plate P to be bent, and the scopes 157 and158 are carried in the rectilinearly disposed brackets 162 and 163. Thescope 158 and its bracket 163 are shown to advantage upon an enlargedscale in FIGURES 13 and 14 of the drawings.

Directly beneath the position which the scope158 will occupy, the baseblock 61 is drilled to provide a recess or pocket 165 and fixed Withinthe recess is a cylindrical block 166 preferably made of brass andinscribed upon its upper surface with cross lines as at 167. There arefour of these blocks 166, one beneath each of the scopes adjacent to thefour corners of the plate, and the linear and transverse measurementsbetween the crosshairs of adjacent scopes are very accuratelypredetermined.

The bracket 163 as shown in FIGURES 13 and 14, has its'shank end drilledat three places to receive the bolt 168 and the dowel pins 169. Bolt 168is threaded into the base block 61 as at 1761 and the dowel pins 169 arefitted closely in hardened steel bushings 172 which are pressed into therecess 173 in the block.

The forward end of the bracket 163 is bifurcated as at 175 and adaptedto receive the optical scope 158 which is of cylindrical configurationand may be provided with any suitable system of lenses, suggested at176, and with crosshairs 177 which are brought into exact register withthe cross marks 167 on the brassblock 166 for a preliminary setting. Thebifurcated end 175 of the bracket 163 may be brought into close grippingcontact with the scope 158 by means of the bolt 179. It will be notedthat the forward end of the bracket 163 is indicated to provide a slot181) for the reception of the edge of the plate P. The plate P, as shownin FIGURE 13, is provided with cross gauge marks 187 which will bebrought into alignment with the crosshairs 177 of the scope 158 when theplate is in properly located position.

The scope and bracket installation 1157, 162 will be identical with theone just described in connection with FIGURES 13 and 14 of the drawings,except in reversed position. The scopes 155 and 156 (160 and 161) aresimilarly formed, equipped, and fastened, except that they are disposed'at a 45 angle with the edges 152 of plate P, and the undercut ornotched portion 181} is V-shaped at its inner extremity as clearly shownin the upper portions of FIGURE 12. I

The operation of the device in forming the novel plate configurationswill be readily understood from the following description: The clampingbars and as well as the bending bars 80 and are removed from the jig andthe plate P is placed on the jig and lined up, according to one method,by bringing the inscribed lines or register marks 151 on the plate Pinto alignment with the inscribed gauge marks 151 on the insert ateither side of the jig. The register marks 151' are placed on the plateby the plate maker in accurate relation to the image on the plate. Thiswill locate the plate quite accurately in the jig. Then the clamp barsare replaced into position, the plate securely clamped adjacent itsends, the bending bars installed, and then swung downwardly to throw thebends into the respective ends of the plate.

In using the scopes, the operator will locate the plate approximately onthe bending jig, then place the clamp bars in position and snug down theplate on the jig.

He will then takeflthet four; optiealscopes as they,.are mer nte d, ontheir supporting brackets and pliCfi. the" seniblyintoposition overtheiplaite? new i j nm ye; the plate until the four -register 'rn'arks'inscribed 'on' the; plate coincide with the crosshairs in the fou rscopes; Finally he willfclarnp the; plate tightly andfrnalie the l nd v.i J t At any time during the life oi the bending jig the operatoii'cancheck the accuracy ofithe seopes against the cros shair s whichareperrnanently loeated'on .th'e'jigsf on the plngslfi, l

In thebending operation, the movement of the leading edge bending bar seis'elearly shoxvnin FIGURES of the drawings, the initialposition'beingindicated in solidi lines and the dotted line positionshowing the .trltiniafe' end of the swinging movement where the' heel;portion of the plate has been swung downwardly and inwardly against theunderside of the" ledge 65. At the tail: end of the device thedownwardly swinging r'novernentof the bending bar 125, 140 from thesolid line position tofthe dotted line position effects the double bendin that endof the plate. i i

Upward swinging return movement of the bending bars and the releasing oftheyclampingbars frees'the' plate for removal and application to theplate cylinder of the press. v

It is understood, that Various changes and modifications rnay beir nadein the illusti ative embodiment of the invention set forth hereinwithout departing" front the" seopeof the invention as definedx by'thelfollowing clainisi Having thus described the invention, vvhat is claimedas new and desired to be secured by Letters Patent. isz' l. A printingplate for application to the printing cylinder of a lithographic oflsetprinting press, said plate: being (if-conventional substantiallyuniformthickness and having a tail edge portion bent away from the irnprsf sionface of the plate to form the inwardly. directed flanged edge portionsfor seizure by gripping means in; the cylinder gap, a hook flange formedon the leading" edge. of the plate for anchoring engagement with thesimilarly angled edge of the cylinder gap, and an arcuate portionimmediately adjacent the hook flange at the eading edge, said arcuateportion impressed upon the plate to curve it uniformly and withoutvariation, in the,

H .t i. l

' to the plate'fcylin'der of an eff set printing press ture being oonvexupon the iiiipres'sion s'ide of the plate and of a "radius somewhat lessthanjth'at of plate elditqe i at wax m ineir pr g office f aiep a mg;edge, isle id "a'rcuate portion impressed upon' the plate sof'the'plat'ein adireetion' aviay from the ir'npfre s'sion faqe' offthepl'at e, andupon a radius sometha'ii that of tlie plate cylinderto Which the lessplate is' to" he'fapplied 3i The"met h6tl of preparing a lithographicplate of conventionalsubstantially uniform thickness for applieajcomprises the steps'gof' bending flange: at the tail edge of the plateas'forengagenient by' gripping means ga ofth'e plate cylinderfbending ahook flange a't'the leading'e'dge of tliejla'te for; engagement with aponding'angled edgefof the plat yli1ider' gap,

and inipress ng uponfthe plate a'curva'tltire' throughout a "s'rnall'a'r'cua te egit'e'ntirninediatelfadjaeent s aid hook the #9 aee iaei ia e a e -Re ferenc es Cited in the file of this patent UNIIED. TA S EANT 1 55 05 Me se et a M r 1 32 2,192,924 Maher'et al. Mar. 12, 19402,285,1l v; Grgupe June 4 23115 852, Durh arn Dee. 22 19.42 ,609 142 ettwj i se a 63i l is Amen De i 1 5 2,619,279, 'Sehgva rtz et al, May 25,i954. 9,Q Q i i g V p printing i press; said plate a u 'ddnventionalsubstantiallf'nniform thickness aiid havin'gata il edge portionheiit'away'fronl the irri-f' the inwardly directedv r t. 3 3N53 l' i aan he an e an: r -6 n r d on} h a n edge off't h'e platefiof'anchorihgengagement with the si'rnil'arl'y angled edgeoi the Cylinder gap; andanarcuate funifornily' and without variation, in the gen

